台灣產南洋紅豆杉之內生真菌對植物病原真菌及松材線蟲之拮抗作用

Abstract

中文摘要 以台灣大學植物病理與微生物學系應用微生物研究室所保存之分離自健康台灣產南洋紅豆杉(Taxus sumatrana (Mig.) de Laub.)之內生真菌300株作為研究材料，首先進行菌種活化，以作為檢測拮抗作用素材。經初步篩選162株生長速率較一致的內生真菌，並與立枯絲核菌(Rhizoctonia solani Kühn)進行對峙培養，再鏡檢其拮抗作用。結果顯示共48株內生真菌可對立枯絲核菌產生拮抗作用，其作用模式可歸類為：纏繞、侵入，或促使寄菌絲油滴狀化、扭曲變形、抑制生長；纏繞後侵入、纏繞後產生附著器、附著後侵入生長、侵入後產生油滴現象、扭曲與侵入內部生長等單一或不同組合之拮抗現象，造成寄主被毀而崩解。繼而以經初篩檢具較顯著拮抗作用之48株內生真菌，對18種不同之重要植物病原真菌以及松材線蟲再進行拮抗作用檢測，結果顯示各種內生真菌對植物病原菌以及松材線蟲皆有侵染或拮抗之行為。此外亦進行此等具拮抗作用內生真菌之形態、構造特徵，輔以rDNA之序列指紋進行鑑定，比對NCBI之基因資料庫，結果顯示此等內生真菌皆以子囊菌居多，此和以往一些國外學者所發現之內生真菌有所雷同，但也有本土特異性之菌株存在，値得更進一步探討。由初步檢測內生菌對重要病原所顯示之顯著拮抗作用，但於自然界卻對南洋紅豆杉無明顯不良影響，此也意涵其未來於生物防治或發展生物防治劑之潛在應用能力，尤其是對於苗木之強化和病害之預防，罹病性之降低等應會有所助益。

Abstract Of the 300 fungal endophytes isolated from healthy Ｔaiwan yew Taxus sumatrana, which preserved in the Applied Mycology Laboratory, Department of Plant Pathology and Microbiology, National Taiwan University, were selected and used to test their antagonistic activity towards plant causal organisms. After preliminary screening, 162 strains were chosen for dual culture with Rhizoctonia solani, a crop damping-off pathogen, to test antagonistic interactions in vitro. The results showed at least 48 strains of them were able to attack or exert adversal effects on R. solani, either by entwining, forming appressorium and penetration, and resulted in hosts malformation and growth suppression. Usually the hosts were eventually destroyed and lysed by either single or combinative detrimental effects of the endophytes. Further testing interactions of these 48 strains endophytes towards 18 plant fungal pathogens as well as pinewood nematode, Bursaphelenchus xylophilus, were carried out in dual culture in artificial media. Under light- or scanning electron-microscopy, it has been revealed again that many of the attacked etiological organisms or pinewood nematode were either deformed, lysed or their multiplication repressed. Furthermore, the entity of the endophytes were discerned by rDNA (ITS1-5.8S-ITS2) fingerprinting by blasting the genomic database in NCBI, USA. Many of the identified endophytes represented in the phyllum Ascomycota, some were comparable to those of described endophytes, however, several were newly recorded genera or species, with domestic uniqueness and deserved further study. The preliminary exploration implicated that these endophytes possessed potential being used as biocontrol agents, particularly in enhancing the vigority and preventing the decline or seedling disease in nursery.